The present disclosure relates to a non-volatile memory device, a non-volatile memory control device, and a non-volatile memory control method which can prevent speed reduction caused by a small-sized access.
Recently, a NAND flash has been widely used as a non-volatile memory. In a storage device using the NAND flash, write speed of electronic data changes depending on a write size. Processing called a garbage collection has a large effect on the change (refer to Patent Documents 1 and 2). Since this operation is performed independently from an access by a host device for performing a write to the NAND flash, the operation is associated with instantaneous and rapid reduction of access speed. Therefore, it is necessary to reduce a frequency of the garbage collection to maintain performance.
In a general flash memory device, data written in a flash memory is divided into two kinds, that is, a block unit and a page unit, and managed. Management is performed in which an integral multiple of a block size of the flash memory (referred to as a block unit below) is assumed as one unit in block unit management, and management is performed in which an integral multiple of a page size of the same flash memory (referred to as a page unit below) is assumed as one unit in page unit management. The block includes a plurality of pages. Therefore, it normally becomes (block unit>page unit).
A garbage collection is an operation in which regions managed by the page unit are collected and promoted to the management by the block unit. Therefore, when the write is performed so that the management by the block unit is performed from the beginning, generation of the garbage collection can be prevented. This can be realized by performing the write with the integral multiple of the block units. Therefore, in a case where it is necessary to perform high-speed write, a method in which an access is performed by the integral multiple of the block units has conventionally been used.